Here is the Library of Congress Classification list of labor studies topics (with call numbers.)
HD4801-8943 Labor. Work. Working class
HD4861-4895 Labor systems
HD4909-5100.9 Wages
HD5106-5267 Hours of labor. Including overtime, shift work, sick leave, vacations
HD5306-5474 Labor disputes. Strikes and lockouts
HD5481-5630.7 Industrial arbitration. Mediation and conciliation
HD5650-5660 Employee participation in management. Employee ownership. Industrial democracy. Works councils
HD5701-6000.9 Labor market. Labor supply. Labor demand. Including unemployment, manpower policy, occupational training, employment agencies
HD6050-6305 Classes of labor. Including women, children, students, middle-aged and older persons, minorities
HD6350-6940.7 Trade unions. Labor unions. Workers' associations
HD6941-6948 Employers' associations
HD6951-6957 Industrial sociology. Social conditions of labor
HD6958.5-6976 Industrial relations
HD6977-7080 Cost and standard of living
HD7088-7252 Social insurance. Social security. Pension
HD7255-7256 Vocational rehabilitation. Employment of people with disabilities
HD7260-7780.8 Industrial hygiene. Industrial welfare
HD7795-8027 Labor policy. Labor and the state
HD8031 Labor in politics. Political activity of the working class
HD8038 Professions (General). Professional employees
HD8039 By industry or trade
HD8045-8943 By region or country
HD9000-9999 Special industries and trades
HD9000-9495 Agricultural industries
HD9502-9502.5 Energy industries. Energy policy. Fuel trade
HD9506-9624 Mineral industries. Metal trade
HD9650-9663 Chemical industries
HD9665-9675 Pharmaceutical industry
HD9680-9714 Mechanical industries. Including electric utilities, electronic industries, and machinery
HD9715-9717.5 Construction industry
HD9720-9975 Manufacturing industries
HD9999 Miscellaneous industries and trades